Safety control device for elevators



March 18, 1952 J. BOROVEC SAFETY CONTROL DEVICE FOR ELEVATORS Filed May 16, 195o INVENToR.- JOSEPH ESOROVEC BY A a5 ATT'YS Patented Mar. 18, 1952 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to improvements in safety devices for elevators.

It is well recognized that elevators employed in the transport of human beings and property require some means for preventing their overloading so as to reduce to a minimum the possibility of causing injury and/or damage. The practical problem has been how to achieve this result with the smallest possible dependence upon the human factor. Attempts have been made to devise means for warning that an elevator has reached its load capacity and rendering the elevator inoperative if that warning is ignored and the elevator further loaded. However, none of these prior devices has succeeded in providing one that was simple and effectively reliable.

The main objects of this invention, therefore, are to provide an improved automatic means for iirst indicating to an elevator operator that a safe load limit has been reached and subsequently immobilizing the elevator if the warning of load limit is ignored and more load placed upon the elevator; to provide improved means of this kind for electrically powered elevators which operate one signal when the load limit is reached and cut out the elevator power and simultaneously operate a second signal to indicate such elevator immobilization when that safe load limit is exceeded; to provide an improved load-capacity switch for neutralizing the over-load power immobilizing means when the elevator is abruptly started with a full load, thereby eliminating the likelihood of an intermittent stopping and starting of the elevator because of an excessive bounce or spring in the cable hitch; and to provide an improved load limit and over-load limit signal and power-immobilizing device of this kind which is extremely simple in construction, hence economical to manufacture, which is highly efficient and reliable in operation, and which is capable of attachment to practically any standard elevator.

In the particular embodiment shown in the accompanying drawings:

Figure l is a perspective view of a skeleton elevator showing `the mounting thereon of an improved safety device involving this invention.

Fig. 2 is an enlarged, fragmentary view of the elevator hitch beam showing the manner of mounting this improved safety device thereon, part of the housing of the main switch for this safety device being broken away to more clearly show the interior arrangement thereof.

Fig. 3 is an enlarged, fragmentary, sectional view of the main switch for this improved safety device.

Fig. 4 is a perspective View of one of the block clamps whereby the main switch-mounting bar is secured to the hitch beam of an elevator; and

Fig. 5 is a diagram of the wiring required for the operation of the several parts of this improved safety device.

Whether an elevator is used for passenger or freight service, there is always a tendency on the part of some operators to crowd in as many people as possible, especially when the people are standing at an entrance awaiting transport, or to load on all the freight which space and stacking will permit, regardless of the resulting overall weight. Accordingly, elevators are often loaded beyond what is safe to the immediate concern of the passengers, the possible damage to the merchandise, and the ultimate condition of the elevator. Therefore, it is advantageous to have some means for reasonably protecting people, merchandise, and elevators from possible injury, damage, and abuse at the hands of such operators. To this end the instant invention provides for a signal when the load-limit is reached and means for immobilizing the elevator operating circuit and a signaling of that fact when the load-limit signal is ignored by the operator and the elevator loaded beyond safe load limit.

The particular embodiment of an elevator safety device shown in the accompanying drawings, constructed in accordance with this invention for use with an elevator 6, comprises a main switch 1, and a mounting bar 8 for securing the switch 'l in position to be actuated by the deflexure in a hitch beam 9 of the elevator 6 so as to successively operate a load-limit signal I0 and an elevator immobilizing switch means II and an over-load signal I2. All of these, and a switch means I3 for neutralizing the immcbilizing switch means II, are operatively related to electrical circuits I 4, I4 and I 5 and the elevator control circuit C.

The elevator 6 is herein shown in skeleton form with its platform I6, whereon is mounted a suitable car (not shown), supported on bottom cross beams I1 secured to side beams I8 suspended from the hitch beam 9 to which is attached cables I9 for supporting and moving the elevator platform I6 (and its car) in its ascent and descent along guide rails 20. Guide shoes 2l secured to the upper ends of the hitch beam 9 embrace the side rails 20 and secure the car against horizontal movement.

The main switch 'I embodying this invention comprises a housing 22 wherein is arranged a contact box 23 mounted on a rocker arm 24.

The rocker arm 24 is tensioned by a spring 25 to depress a switch member 26, in the form of a plunger, and hold the switch contact pins 21 and 28 retracted from the adjustable posts 29 and 30 and therefore out of engagement with contacts 3l and 32 (see Fig. 5) in the circuits I4 and I4 respectively. A conduit 34 leads in through the switch housing 22, being secured thereto inthe usual manner. The wires in the conduit are appropriately connected to the parts as indicated in the diagram shown in Fig. 5.

The housing 22 is shown bolted to an angle plate 22.I bonded to the mounting bar and provided with a removable cover 22.2.

The contact box 23 and its associated parts is a conventional device for various usesv incontrolling electrical circuits. It is suitably secured by bolts 33 to the rocker arm 24 (see Figs. 2 and 3). 'I'he switch contact pins 21 and 28 are mounted in sleeves 35 and 36 secured to the contact box 23 in alinement with the posts 29 and 38. These pins are normally retracted by springs (not shown) from the circuit contacts (not shown) in the box 23, indicated at 3l and 32 in the diagram shown in Fig. 5.

The switch member 26 is slidably supported on the housing 22 in -position to abut the bottom of the box 23 and to be contacted by the hitch beam 9, when it is flexed by a load on the elevator 6. Movement of the switch member 26 shifts the contact box against the action of the spring 25 and moves the contact pins 21 and 28 into contact with the posts 29 and 30 with their consequent successive engagement with the contacts ,3| and 32 and the closing of the circuits I4V and The mounting bar 8, as herein shown, is in the form of an angle bar, with the main switch 1 secured thereto intermediate its ends, as above noted. The bar 8 is anchored to the hitch beam 9 parallel to and above the top flange of the hitch beam 9 by clamps 40.

The clamps 40 are in the form of blocks and are slotted at 4I and 42 to fit over the top ange on the hitch beam 9 and the mounting bar 8 respectively. Pairs of set screws 38 and 39 opposed to the slots 4I and 42 secure the block clamps 4I)V to the mounting bar 8 and hitch beam 9.

The slots 4I and 42 are so formed that the dimension X (see Fig. 4) will so dispose the switch member 26 with respect to the upper face of the upper flange of the hitch beam 9 that when the elevator -6 is without load, the switch member 26 will be depressed and the contact pins 21 and 28 held out of contact with the posts 29 and 39, and consequently out of engagement with the contacts 2I and 22 leaving the circuits I4 and I4' open. As the platform I6 is loaded, the flexure of the hitch beam 9, as a consequence of its central suspension, gradually shifts the member 26 to move the contact box 23 against the action of the spring 25 until. contact of the switch pins 21 and 28 against the posts 29 and 3U cause the engagement of thecontact pins 21 and 28 with the contacts 3| and 32.

The signals I and l2 are herein shown as different colored light bulbs, one white (W), and the other red (R), interposed in the circuits I4 and I4' respectively.

The immobilizing switch means I I comprises a pair of switches 43 and 44, the switch arms for which are connected to an armature 45 so as to move in unison. The contacts for the switch 43 are connected in the circuit I (see Fig. 5) whereasV the contacts for the switch 44 are connected 4 in the elevator control circuit C. The solenoid 46 is connected in the circuit I4. Thus this switch means II serves to open the elevator control circuit C and simultaneously illuminate the lamp I2 when the elevator car platform I6 is loaded beyond safe load-limit.

The neutralizing switch means I3 comprises a switch 41 and a solenoid 48, the armature 49 of which is connected to the contact member of the switch 41. The contacts for the switch 41 are connected in the circuit I4 Whereas the solenoid 48 is connected in the circuit C. This switch means I3 serves to cut out the immobilizing switchY means I l wheneverthe circuit I4 is closed. Thus, if the elevator is operated with a limit load, there is no possibility of the elevator intermittently starting and stopping, due to the spring in the hitch beam 9 in case the start of the elevator is rather sudden.

The operation of this improved safety device is substantially as follows:

So long as the elevator 6V takes on a load no greater than the authorized safety load-limit, the main switch 1 is inactive. The hitch beam 9 may flex a bit as loads are taken on and off, but there will not be enough movement of the switch member 26 to effect an engagement of switch pins 21 and 28 withv their respective contacts 3i and 32. However, as soon as the platform IlB, of the elevator 6, is loaded to authorized capacity, the flexure of the hitch beam 9 will be sulcient to elevate the switch member 26 and cause the upward swing of the rocker arm 24 suicient to move the switch pin 21 into contact with post 29. The resulting depression of the pin 21 will engage it with the contact 3ly and close the circuit I4. The illumination of the lamp I0 follows, thereby notifying the car operator that the load-limit has been reached.

When the load-limit on the platform I6 has been reached but not exceeded and the circuit C is closed to start the car, the solenoid I48 is energized, thereby opening thev switch 41 and rendering the immobilizing switch means II inoperative. Accordingly, any further deexure of the hitch beam 9, due to starting the car with only a limit-load thereon, will not eiect a functioning of the immobilization switch means I I.

If, after the safe load-limit has been reached, the operator continues to take on additional passengers or packages, the consequent addtional exure of the hitch beam 9 moves the switch member 26 to bring the switch pin 28 into contact with the post 30, thereby causing the engagement of the pin 28 with the contact 32. Thereupon the circuit I4 is closed, resulting in an energization of the solenoid 46 of the switch means II. The shifting of the armature 45 opens the circuit C and at the same time closes the circuit I5. AOpening the circuit C immobilizes the elevator so long as an overload weight rests on the platform I6. The closing of the circuit I 5 illuminates the red light I2 thereby signalling to the elevator operator that the car has become inoperative.

Adjustment of the posts 29 and 30 insures the proper sequential engagement of the contact pins 21 and 28 with the contacts 3I and 32 as may be required to secure the desired operation of the load-limit signal I0 and the immobilizing switch means I I consistent with the fiexing of the hitch beam 9.

The circuit herein shown is also provided with the usual manually operated cutout switch III for opening and closing the entire circuit.

Variations and modications in the detail oi.' structure and arrangement of the parts may be resorted to within the spirit and the coverage of the following claims.

I claim:

1. An elevator safety device of the class described comprising, an elevator control circuit, a switch mounting two pairs of normally open contacts, a switch member movable to successively effect the closing of said pairs of contacts, a signal, a pair of switches one of which is located in said elevator control circuit, a solenoid connected to simultaneously operate said pairs of switches, a second signal, circuits respectively connecting in parallel one pair of said contacts and said first-mentioned signal and the other pair of said contacts and said solenoid with a source of electrical energy, and a third circuit connecting the other solenoid-operated switch and said second signal with said source of electrical energy, said switch member being positionable to be actuated by the defiexure in the hitch beam of an elevator for successively closing said pairs of contacts to effect the successive operation of said first-mentioned signal and said solenoid to respectively indicate a load-limit on said elevator and immobilize its operation when the elevator is overloaded.

2. An elevator safety device of the class described comprising, an elevator control circuit, a switch mounting two pairs of normally open contacts, a switch member movable to successively eiect the closing of said pairs of contacts, a signal, a pair of switches one of which is located in said elevator control circuit, a solenoid connected to simultaneously operate said pairs of switches, a second signal, circuits respectively connecting in parallel one pair of said contacts and said first-mentioned signal and the other pair of said contacts and said solenoid with a source of electrical energy, a third circuit connecting the other solenoid-operated switch and second signal with said source of electrical energy, said switch member being positionable to be actuated by the deiiexure in the hitch beam of an elevator for successively closing said pairs of contacts to effect the successive operation of said rst-mentioned signal and said solenoid to respectively indicate a load-limit on said elevator and immobilize its operation when the elevator is overloaded, and a second solenoid-operated switch, said switch being connected in said third circuit and said solenoid being connected in said elevator control circuit whereby said first solenoid will be neutralized when said elevator is operated with a load-limit.

3. In combination, an elevator having a hitch beam, a switch mounting a pair of normally open contacts, a switch member movable to effect the closing of said contacts, a signal, and an electric circuit connecting said contacts and said signal with a source of electrical energy, said switch member being positioned on said elevator to be actuated by the deflexure in said hitch beam of said elevator to effect the operation of said signal to indicate a load-limit on said elevator.

4. In combination an elevator, an operating control circuit for said elevator, a switch mounting two pairs of normally open ccntacts, a switch member movable to successively effect the closing of said pairs of circuits, a signal. a pair of switches one of which is located in said control circuit, a solenoid located to simultaneously operate said pairs of switches, a-w second signal, circuits respectively connecting in parallel one pair of said switch contacts and said first-mentioned signal and the other pair of said switch contacts and said solenoid with a source of electrical energy, and a third circuit connecting the other solenoid-operated switch and said second signal with said source of electrical energy, said switch member being positioned on said elevator to be actuated by the deflexure in the hitch beam of said elevator to eiect the successive operation of said first-mentioned signal and said solenoid to respectively indicate load-limit on said elevator and immobilize its operation when the elevator is over-loaded.

5. In combination an elevator, an operating control circuit for said elevator, a switch mounting two pairs of normally open contacts, a switch member movable to successively eiect the closing of said pairs of circuits, a signal, a pair of switches one of which is located in said control circuit, a solenoid located to simultaneously operate said pairs of switches, a second signal, circuits respectively connecting in parallel one pair of said switch contacts and said iirst-mentioned signal and the other pair of said switch contacts and said solenoid with a source of electrical energy, a third circuit connecting the other solenoid-operated switch, and said second signal with said source of electrical energy, said switch member being positioned on said elevator to be actuated by the deiiexure in the hitch beam of said elevator to effect the successive operation of said first-mentioned signal and said solenoid to respectively indicate load-limit on said elevator and immobilize its operation when the elevator is over-loaded, and a second solenoid-operated switch, said switch being connected in said third circuit and said solenoid connected in said elevator control circuit whereby said iirst solenoid is neutralized when said elevator is operated with a load-limit.

6. An elevator safety device of the class described comprising, a bar, a switch attached to said bar, said switch mounting a pair of normally open contacts and a switch member movable to effect the closing of said contacts, and means for attaching said bar to the hitch beam of an elevator for locating said switch member to be actuated by the deflexure of said beam to effect the operation of a signal to indicate a load-limit on an elevator.

'7. An elevator safety device of the class described comprising, a bar of a length nearly equal to the length of a hitch beam of an elevator, a switch attached to said bar intermediate the ends thereof, said switch mounting a pair of normally open contacts and a switch member movable to effect the closing of said contacts, and means for attaching the ends of said bar adjacent the ends of said beam so as to locate said switch member in position to be actuated by the deflexure of said switch beam intermediate said bar attachments to eii'ect the operation of a signal to indicate a load-limit on an elevator.

8. In combination an elevator, an operating control circuit for said elevator, a bar of a length nearly equal to the length of the hitch beam of said elevator, a switch attached to said bar intermediate the ends thereof, said switch mounting two pairs of normally open contacts and a switch member movable to successively effect the closing of said pairs of contacts, a signal, a pair of switches one of which is located in said control circuit, a solenoid located to simultaneously operate said pairs of switches, a second signal, circuits respectively connecting in parallel one 7 pair of: said switch contacts and` saidrst-mentioned signal and the other pair of said switch contacts; and said solenoid with a source of electrical energy,v a third circuit connecting the other solenoid-operated switch and said second signal with a source of electrical energy, and means for attaching the ends of said bar adjacent the ends of said beam so as to locate said switch member in position to be actuated by the deexure of said hitch beam intermediate said bar attachments so as to effect the successive operation of said first-mentioned signal and-said solenoid to respectively indicate the load-limit on said elevator vancl'immobiliye itsvoperation when. said elevator is over-loaded.

JOSEPH BOROVEC.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS l0 Number Name Date 1,015,874 Cronk July 30, 1912 1,613,216 Albersheim et al. Jan. 4, 1927 1,640,673 Scheinfeld Aug. 30, 1927 

